Different devices have during a number of years been more and more used for delivering medicament to a patient, such as auto-injectors, inhalers and such where the main reasons being the possibilities for the patients themselves to handle the delivery in an easy, safe and reliable way and also to facilitate the administration of drugs for hospital personnel in a quick, safe and reliable way. Depending on the intended use and the type of medicament, when looking at delivery of liquid drugs such as auto-injectors, they have developed varying degrees of automatic function, ranging from only automatic penetration or only automatic injection to fully automatic function including penetration, injection, withdrawal and shielding of the needle. A number of sub-functions have also been developed such as controlled injection rate, multiple doses with means for varying the quantity of each dose, locking of needle cover before and/or after use, and the like.
As regards the medicament, most types are packaged in cartridges, ampoules or syringes containing a ready-to-use liquid-state medicament, where the medicament is dissolved or suspended with the liquid, where they could be stored for a long time before use. However, some types of medicament cannot be pre-mixed because the medicament becomes degraded and looses its effect rather quickly when mixed with the liquid. Solutions can also have a limited effective time span. With such medicaments the user, patient or nurse/physician, has to perform the mixing within a limited time prior to the delivery. In the case of injecting the medicament, this is usually done such that the medicament in powder or liquid form is arranged in a container, often a small vial. An appropriate liquid is then poured into the vial, which may then need to be shaken in order to dissolve the medicament. A needle of a syringe is then inserted into the bottle and a quantity of the mix is drawn up, either the full content of the bottle or a certain part of it. This procedure is of course rather awkward, in particular for persons not used to handle these devices, and is obviously not suitable for auto-injectors.
In order to facilitate the mixing, cartridges, ampoules or syringes have been developed which contain two chambers, each containing a part of the medicament solution, which, when mixed, forms the medicament to be delivered. The two chambers are sealed off when stored in order that the medicament solution does not become degraded. When the medicament solution is to be mixed, passages are opened between the chambers, usually by depressing the stopper and in turn the divider of the syringe somewhat. The passages allow the mixing of the parts and the medicament is ready for delivery. Up to now these dual chamber cartridges, syringes or ampoules have only been used with ordinary type, manually handled devices. For certain applications and medicaments however, it would be advantageous to use a device in combination with these dual chamber solutions in an easy and user-friendly way in order to obtain the mixing before delivery.